How long does magnesium stay in your body?

Magnesium is an essential mineral that helps your body function properly, from supporting muscles and nerves to keeping your heart rate steady. How long it stays in your system depends on the type of magnesium, how your body absorbs it, and other personal factors, but most types are eliminated within a day or two.

Why Magnesium Half-Life Matters

The half-life of magnesium is approximately 8 to 9 hours, whether it comes from food or supplements. Half-life refers to the time it takes for half of a substance to leave the body.

If you take magnesium, about half will still be in your body 8 to 9 hours later. After another 8 to 9 hours, half of that amount (25%) will remain. This cycle continues until the magnesium is largely eliminated.

However, your body doesn’t get rid of magnesium immediately. A certain amount is stored in your bones and muscles, where it stays much longer, sometimes weeks or even months, depending on your body’s needs and how quickly it is used up.

Certain factors affect how long magnesium stays in the body, including:

1. The form of magnesium

Magnesium supplements come in several forms, each of which is absorbed differently by the body. Additionally, many food sources of magnesium contain different forms.

Common types of magnesium include:

Forms like citrate, glycinate, aspartate, and lactate tend to be absorbed more efficiently, which can keep magnesium circulating in the blood longer.

On the other hand, forms like magnesium oxide are absorbed less efficiently, meaning they increase magnesium levels less and can be excreted more quickly.

Although supplements are usually clear about the forms they contain, getting a variety of food sources of magnesium can help you get a variety.

2. How much magnesium you take

Higher doses of certain forms, such as magnesium citrate, may result in greater absorption.
Supplements typically range from 100 to 400 milligrams or more, usually taken once daily.

The recommended dietary allowance (RDA) for magnesium is:

• 400 to 420 milligrams per day for men
• 310 to 320 milligrams per day for women

Magnesium is also found in many foods, including:

• Pumpkin seeds: 156 milligrams per ounce
• Chia seeds: 111 milligrams per ounce
• Spinach: 78 milligrams per ½ cup (cooked)
• Cashew nuts : 74 milligrams per ounce
• Black beans: 60 milligrams per ½ cup
• Peanut butter: 49 milligrams per 2 tablespoons

3. Your current magnesium levels

If your magnesium levels are low, your body will retain more. But if you already have enough, excess magnesium is usually excreted through urine.

Your body does a great job regulating magnesium levels to maintain balance. Eating a healthy, balanced diet and incorporating various magnesium-rich foods can help ensure healthy magnesium levels.

4. Health Problems and Medications

Certain health conditions can affect how your body absorbs and retains magnesium. Certain conditions can make it harder for your body to retain magnesium.

For example:

Certain medications can also reduce magnesium absorption, including:

Side effects and safety considerations

Getting too much magnesium in food is rare and usually not a major problem. But high doses of supplements can cause side effects like diarrhea, nausea, and stomach cramps.

In rare cases, magnesium toxicity has occurred from taking extremely high doses over time.

It’s a good idea to consult your doctor before taking magnesium supplements, especially if you are taking medications like blood pressure medications, antibiotics, bisphosphonates, diuretics, or PPIs, as these may interact with magnesium.